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he critics of modern systematics are many, but their
legitimate points are few. Some say |
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systematics is a field that is old, uninteresting,
dusty, and not scientific. These people are wrong on
three counts, and right on one. They are wrong that
systematics is uninteresting. When a feathered dinosaur
is discovered in a Chinese fossil bed, or a new monkey
is found in the forests of Brazil, this becomes the
cover of the next issue of Nature or Science. The reason
for this notoriety is systematics, not biochemistry,
molecular genetics, or any other field. They are wrong
that systematics is dusty: The contentious and
fast-moving fields of methodology of systematics and DNA
technology have revolutionized modern phylogenetics.
Indeed, whenever there is a new concept based on new
data and requiring a change in taxonomy, critics of
systematics object to learning a new name (they liked
the old one so much! ), and therefore object to the
growth of systematics because of its dynamic nature.
They are wrong that systematics is unscientific.
Systematic matrices of dozens of taxa and hundreds of
characters represent the most thoroughly examined
hypotheses in all of modern science, because every
character in every species serves to confirm or refute
the hypothesis of relationship. By comparison, whereas a
phylogenetic hypothesis may have thousands of verified
predictions, most experiments in all the rest of biology
have a handful of confirmatory trials to rely upon. |
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ritics are right that systematics is old (it has aged
two and a half centuries since Linnaeus), |
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but this maturity requires the most demanding
scholarship in all of biology. It is not enough to know
the recent work in a given field; one must know all the
history, every author (good or bad), every respective
species concept, every paper in any language the authors
used, every vague meaning of such words as "transition,"
every study of comparative physiology, every life
history strategy, every nuance of climatology of South
Africa, the history of human colonization of the
Pacific, the tectonic history of the Antilles, the
historic sea levels in the Indonesian archipelago, and
anything else that ever touches the taxa under study.
Yes, it is an old science, and therefore should be
awarded, more respect, not less. |
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ystematics is a particularly difficult field because its
central goal is to make sense of all the |
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biological variation we observe around us. This
substantially exceeds climatology, geology, chemistry,
and physics (because of the "variation" part) and leads
to some awkward situations. Systematics aspires to
organize variation in a hierarchy that will have maximum
explanatory power, but there are at least two serious
pitfalls. First, as with the other sciences, biology
sometimes finds that nature did not leave behind enough
information to make well-supported statements regarding
isolated data. Historical questions (like those of
systematics) are famous in this regard because if no one
was there to see the process in question, it might be
impossible to reconstruct it with security. Second,
people are so exceptionally talented at seeing patterns
(even when there is actually no pattern) that they
handsomely support casinos, state lotteries, and bad
taxonomy by the millions. |
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s modern
systematists, we must fulfill three goals consistent
with the general idea of the |
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"scientific method": 1 ) bring
all reliable data into competition to demonstrate their
global strength without favoring some data and
penalizing others a priori; 2) rely upon the basic
principles of the scientific method to judge competing
solutions, particularly Occam's razor that the simplest
solution is to be preferred (the shortest phylogenetic
tree); 3) if, in fact, the data are ambiguous or
otherwise inadequate to solve a given problem, then say
so, and do not make statements that are unsupported. The
point of cladistic systematics is to formalize these
goals, and to present a repeatable method that will
produce phylogenies that are stable in the face of taxa
and characters yet undiscovered or unexplored. This goal
is not to be taken lightly, for if we sacrifice such
stability, then we have made systematics less
scientific. There is no point to classifying things if
the classification will change every time someone
sequences another gene or includes another species. Nor
are the principles to be compromised for circumstances
that a worker claims are "special," because the history
of biological evolution is unique for every species,
genus, family, etc., and if we easily trade away our
standards for "special" cases, then we will soon have no
standards at all. |
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etractors of cladistic methods generally rely on pleas
that violate the three simple rules |
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outlined above, and their arguments commonly make the
following claims: 1) data are "good" or "bad" based on
external theory, and the data are not examined to see
what hierarchy they form by themselves, 2) reject
Occam's razor, the principle that the simplest solution
is to be preferred (the parsimonious tree in a
phylogenetic context), 3) present an unambiguous
solution, whether or not the data are adequate to
support it. In short, they claim that each study, one by
one (and hence, every study in the aggregate), is
"special" with respect to the cold criteria of
scientific method, and thereby they nullify the
"scientific" part of the "scientific method." |
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he future of systematics surely lies in embracing the
same rigorous criteria as other |
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scientific fields, not bargaining out of them. Cladistic
methods, like them or not, are here to stay. |
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